Nowadays, most of the industrial and living sewage from petroleum refineries and chemical plants are treated with activated sludge process, which leads to lots of residual sludge, easy sludge dilation, difficulty in operation and management, high operation cost and larger land being occupied as well. In recent years, a biofilter treatment process is adopted for treating sewage by many enterprises both domestic and abroad. But it can only be operated in low organic burden because of its low sludge removing rate. Some plants adopt a combined biofilter-contact oxidationactivated sludge series process, which still has the following disadvantages, such as occupying large land, high running cost and complicated operation et al.